I'm kicking about with a story where someone will be under the Imperius and I realised I had a few questions about it.

When someone is under a long-term Imperius (like Barty Crouch Sr) how does it work? Do they carry on with their everyday lives as normal, but with the command they've been given affecting their actions?

How do the orders they've been given work? Is it a sort of overriding objective or it it a series of specific commands? Can their orders be varied at a later date? Can they only be varied by the person who cast the Curse? What about where Voldemort has Imperiused members of the Ministry in the past, because surely he doesn't want to have to see the person under the Curse every time he has to get the information? Could the Death Eaters vary the orders of someone that Voldemort had Imperiused?

Would there be any signs that someone was under the Imperius apart from uncharacteristic behaviour? Might there for example be something a little empty in their eyes or anything similar?

What about if someone was starting to shake off a long-term Imperius, like Barty Crouch Sr did? Would it be a gradual process or a sudden thing? Would it always manifest itself in the seeming mad way it did with Crouch or might it be more subtle with moments of increased lucidity? Could they eventually shake it off completely?

Is there anything else that could break an Imperius other than the victim's own will or its removal, for example would sudden trauma break it?

Finally, are there any limits on what you could make someone do under the Imperius?

Any opinions would be much appreciated,